TWI441691B - Device for characterisation of the granulometry of powders and its uses - Google Patents

Description

Device for characterizing particle size measurement of powder and method of use thereof

The section of the device and the device according to the invention which allows the determination of the particle size of the powder, in particular, can be carried out on the line, that is to say in the progression of the manufacturing process of the powders.

Such related powders are more particularly dry powders, i.e., powders having a water content of less than 5 mass percent, as determined by differential weighing measurements before and after drying of the powders.

The related powders also have a broad particle size measurement range, i.e., the powder has an average diameter between 0.05 and 10 mm.

These related powders are even more special powders used in the production of such foods, such as powders based on sugar crystals, salt powder, flour, milk powder, powders composed of dehydrated food materials, washing powder, ceramics. Powder, plastic powder, metal powder, paint powder, pharmaceutical powder, toner for printing, fertilizer, or powder composed of mineral matter again, and even more particularly natural and/or precipitated based on calcium carbonate And/or a mineral powder based on dolomite and/or based on talc, and even more particularly a powder having a mineral material based on natural calcium carbonate, which is marble, chalk, limestone, Or a mixture thereof.

The first object of the present invention is a device for controlling the particle size of a powder, the device being provided with a feeding mechanism, an emptying mechanism, a weighing mechanism, a continuous vibration mechanism, a screening mechanism, and possibly a control a mechanism, and characterized in that: - wherein the screening mechanism is a mechanism that rotates about a horizontal axis, having at least one position for an unoccupied space or a space for release and introduction of powder, for 1 position of an impact resistant plate member, at least 2 positions of 2 screens for different mesh openings; and wherein the device has a cleaning mechanism consisting of at least one nozzle and/or one at the screening mechanism An ultrasonic generator on the periphery; and the device has an elastic coupling mechanism between the horizontal axis of the screening mechanism and the continuous vibration mechanism.

Another object of the invention is to use such a device for the characteristics of the particle size measurement of the powder, and in particular for its on-line, i.e., the progress of its process.

This relates in particular to dry powders, i.e. powders having a water content of less than 5 mass percent, as determined by the measurement of differential weighing before and after drying of the powders.

It is also related to powders having a broad particle size measurement range, i.e., the average diameter of the powder is between 0.05 and 10 mm.

Finally, it relates to powders used in the production of foods, such as powders based on sugar crystals, salt powder, flour, milk powder, powders composed of dehydrated food materials, washing powder, ceramic powder, plastic powder, metal Powder, paint powder, pharmaceutical powder, toner for printing, fertilizer, or powder composed of mineral matter again, and even more particularly natural and/or precipitated based on calcium carbonate and/or dolomite A mineral-based powder, and even more particularly a powder having a mineral material based on natural calcium carbonate, which is marble, chalk, limestone, or a mixture thereof.

A first object of the present invention is a device capable of characterizing the particle size measurement of various powders as much as possible, such as a dry powder, as defined above, and having a broad particle size measurement, As defined above, and especially for different classes of powders, as defined in this prior section.

By means of the on-line characteristic of the particle size measurement, when referring to a powder consisting of mineral materials, the applicant means particle size measurement during the manufacturing process of the powders, and especially during the process of reducing the particle size measurement of the powder. control.

Another object of the present invention is to provide an apparatus capable of characterizing different particle size measurement categories in the operation of such powders.

Another object of the present invention is to produce the fact that the device made in this manner is simple to use in the manufacture of such powders and is compatible with the industrial constraints of the site.

Another object of the present invention is to provide a device capable of enabling the character description of the particle size measurement during the manufacturing process without altering the powder or damaging the device: the particulate material for analysis Integrity is maintained by this mechanism and maintains the life of the device over time.

Another object of the present invention is to provide automatic cleaning of the device (without operator manipulation), both to reduce the cost of maintenance and to maintain the integrity of the device and the integrity of its results.

A final object of the present invention is to provide a device that allows for the description of the characteristics of the particle size measurement of such powders, where the weighing system is not damaged by vibrations originating from the continuous vibrating mechanism.

It should be noted that the present invention must achieve these last three objectives (preservation of such powders and devices, automatic cleaning, elimination of vibrations), wherein the features that contribute to achieving these objectives are mandatory and non-selective. This is a fundamental difference compared to French Patent No. 0504917.

In the field of powders, the control of particle size measurement is an essential element for those skilled in the art, an industrial process engineer who knows a lot of knowledge, and a technician who specializes in powder materials. In fact, in the case of mineral material powders, this control enables him to understand the quality of the products made in the course of the different stages of particle size reduction. In the more general field of dry powders, and especially in the field of mineral powders, plastic powders, metal powders, ceramic powders, or detergents, and sugars, this control can also be made by the skilled person. The effectiveness of the process is self-confident, while ensuring precise specifications for the end customer in terms of the fineness and size of the particles.

In the field of sugars, it is well known that the size distribution of the individual crystals affects the melting of the sugar pieces formed by the crystals in water, such as "melting of sugar" (Zuckerindustrie Berlin, 1990 (4) ), as described in pages 250-60).

The same principle can be applied, among other things, to the cleaning of crayons whose solubility in water is affected by the size distribution of the individual particles constituting them, and the same factors also affect the fluidity of the powders, such as The document is taught by the document "Production of a granular laundry detergent using a pneumatic nozzle" (Inzynieria i Aparatura Chemiczna (1996), 35(3), pp. 15-18).

In the field of ceramics, it is also well known that the particle size distribution of a calcium carbonate powder can have an effect on the flowability properties of the powder or on the drying of the ceramic material comprising the powder, such as in "calcium carbonate. The effect of the average particle size on the drying shrinkage behavior of the strip smelting body" (The first China International Conference on High Performance Ceramics, Beijing, China, October 31-November 3, 1998 (1999) The record of the activity, as indicated in the date of the meeting, pages 181-184 of 1998).

It is also well known in the field of powders used in the plastics industry that this particle size measurement distribution plays an important role in the fluidity of such powders. This same principle can be applied to metal powders.

Finally, in the mineral industry, it is well known that this same particle size measurement distribution of powders is a fundamental factor that can affect many of the properties of the final product comprising such powders, especially calcium carbonate based powders. In fact, many jobs link this distribution of particle size to the dissolution of calcium carbonate ("the melting kinetics of CaCO ₃ in powder form and the effect of particle size and pretreatment on the melting process", industrial and engineering chemistry studies (1996), 35(2), pp. 465-74), mechanical properties linked to plastic components containing calcium carbonate ("Effects of CaCO ₃ particle size grading on the flow properties of polypropylene", Feijinshukuang , (2001), 24(2), pp. 13-14), optical properties linked to paper sheets made from paper coatings containing calcium carbonate ("Poreed calcium carbonate particle size applied to color rheology "The effect of learning and the nature of coated paper", Kami Pa Gikyoshi, (1999), 53(9), pp. 1174-1178), or reattachment to the structure of a coating film containing calcium carbonate ("Using mercury pores" The influence of the particle size distribution of natural calcium carbonate on the structure of coating films by degree measurement", Double Liaison-Chimie des Peintures [Chemistry of Paints], (1986), 33 (372), pp. 25-37, VIII -XVIII).

In order to control the particle size measurement of such powders, especially in the mineral industry, it is necessary for the skilled person to have a device which is easy to install during its manufacture and which is simple to use; The process of reducing the particle size measurement of mineral matter is used on-line (to control its fineness at a given point in the process - typically at the output of a grinding and / or selection device); - its industry with a production site The constraints are compatible (such as vibrations associated with the use of the grinder, impacts inherent in the movement of various items of equipment, atmospheres typically having a high particulate content, etc.).

In order to characterize the particle size measurement of various powders, it is well known on a laboratory scale to use optical techniques such as by electron transfer through diffusion, methods based on the gas adsorption, optical resources based on Axel diffraction. , traditional optical microscopes, or true laser technology. Thus, in order to measure the distinctive dimensions of alumina powder in the ceramic field, the document "Comparison of various particle size grading techniques" (Wuhan University Technical Journal, Materials Science Edition, 2000, pp. 7-14) reports these Use of technology.

As examples of commercial equipment used to determine the particle size distribution of the powder is measured, and use some of the prior art addressed, the applicant can be cited range by a Malvern Mastersizer ^{TM TM} of the company made laser particle sizer of the laboratory , the range of the Insitec laser particle sizer ^TM made online by the same company, and by the company Micromeritics Sedigraph ^(TM) type made of apparatus, which is based on X-ray diffraction techniques.

So, in order to determine the size of the crystals of sugar, for by areas of concern of the present invention, the file (University of Queensland, chemical department of the paper, 1E0406 / 7, 2000) "alcoholic sucrose crystallization" Report a Mastersizer ^TM The use of a particle size measuring instrument. This same device has been successfully used to determine the particle size measurement of plastic materials, such as "analysis of the physical properties and simplicity of direct compression bonding agents commonly used" (AAPS PharmSciTech. 2003, 4(4), Article 62 The person described in ). Similarly, "colloidal processing of hydroxyapatite" (biomaterials, 22,2001, pp. 1847-1852) using a Sedigraph ^TM 5100 about the type of device to determine the manufacturing of ceramic materials such as The particle size distribution distribution of the hydroxyapatite powder used.

It is also known to use measurement devices in the general field of powder particle size measurement based on analysis of images performed using a camera. Those skilled in the art department familiar with this area, and has a name by the Retsch Technology ^TM company sold the equipment to Camsizer ^TM, by Haver and Boecker ^TM sold the company's CPA ^TM, or by another company Norske Hydro ^TM Part An ^TM sold.

However, such devices have a number of disadvantages. Depending on the device, the measurement range of the particle size measurement is narrow. These devices specialize in a measurement range. They cannot be measured immediately over a range of tens of microns to a few millimeters. Through the use of technologies such as lasers and cameras, these results are derived from statistical calculations: they need to be adjusted by interrelationships, which takes considerable time to calculate. This statistical method cannot give the percentage of the product, which is necessary for the quality of the delivered product. Moreover, these precision devices are difficult to comply with the vibrations inherent in the equipment of certain items, such as the presence of grinders, which are often found in the mineral industry. These vibrations also interfere with such devices, and the measurement range of the particle size measurement is relatively wide. For example, an optical system by image analysis cannot obtain a desired image quality due to its excessive depth of field, so as to fully describe the The characteristics of the resulting powder, except by the use of microscopic measurement of image refinement techniques, are unstable in a restricted industrial environment (vibration, etc.).

In addition, several devices are quite expensive; they use techniques that are typically lengthy and excessively fine adjustments of the sample to be analyzed under severe cleaning conditions, in the case of a mineral material manufacturing unit (there is Among the powdery substances, it is sometimes difficult to obtain. Moreover, certain techniques are capable of characterizing only a very small amount (a few grams) of powder, which poses a problem of the representativeness of the actual production capacity of such samples relative to most industrial equipment. Finally, for the purpose of on-line measurement of the particle size measurement of these already made powders, some measuring devices - by themselves - will have to undergo many modifications in order to be used at one precise location in the manufacturing process, which is proficient for such The artist constitutes this primary need.

Therefore, based on its size, the use of mechanical devices, sieves, screens, nets, or springs, those skilled in the art would prefer to select devices that involve feature description based on the choice of particles. In each of these categories, the Applicant will now review the documents available to those skilled in the art.

The types of devices based on screens, screens and nets are very large. Thus, the applicant indicates that the B07B level of the International Patent Classification (eighth revision) contains more than 17,789 documents on the filing date of this application, relating to sieves, screens, and solid materials using nettings and grilles. Classification or comparable system.

Among them, however, it is possible to use different geometrically shaped rotating and/or vibrating screens to distinguish devices. Thus, U.S. Patent No. 4,184,944 describes a cylindrical screen apparatus which is continuously rotated about its horizontal axis and which is capable of drying or damping the powder to screen through a screen surrounding the cylinder. At the same time, the European patent document EP 1 163 958 presents a cylindrical device which continuously rotates at its horizontal axis, where the horizontal movement is accomplished by a vibrating movement applied to the screen forming the cylinder: This device is specifically intended for screening soil-based materials.

In general, the Applicant indicates the use of the cylindrical cage, which is covered with a screen and moves with a rotary and/or vibrating movement so as to be able to screen mineral particles and is familiar to the skilled person. A well-known institution. Secondly, in addition to the above-mentioned devices, it is common to weigh the screened materials in such a manner that a mass ratio of the particles is obtained, the diameter of the particles being less than the screen used. Screen hole. However, these devices are not satisfactory to those skilled in the art because they are used industrially to separate materials of different nature and/or to clean materials contaminated with particles measured by very different particle sizes. Therefore, they are not intended to describe the characteristics of the powder. Moreover, these devices are equipped with a single type of screen covering the entire circumference thereof and are only capable of characterizing the particles of a single particle size measurement. Moreover, none of these devices expose systems that measure the particle size of the powder on-line.

In the category of devices based on screens, screens or other grids, the applicant is finally familiar with U.S. Patent No. 4,487,323, the disclosure of which is incorporated herein incorporated by its entirety in The characteristics of the particle size measurement of the powder are described, which have an opening and a different screen. The drum is moved to its different positions around its axis and is agitated by a vibration motor that allows screening of the powder, the powder comprising powder passing through the screen, the powder being directed downward. A balance located below the drum and separated by the system enables the mass of particles that have passed through each screen to be quantified. However, such a device is not capable of characterizing the particle size measurement of the powder on-line because the operator must manually place the powder for testing within the drum.

Those skilled in the art therefore turn to the category of devices for measuring the particle size measurement of powders, especially through the use of springs.

This technique has actually appeared more recently than it has been discussed above (and it is based on grids, screens or screens). Therefore, the number of files it contains is much smaller, and it is easier for those skilled in the art to quickly recognize the devices, and during their manufacturing process, the devices are as capable as possible to solve the problem of being written online as much as possible. The problem of the characteristics of the particle size measurement of the powder.

Thus, the skilled person is acquainted with the recent U.S. Patent No. 6,829,955 B1 (issued on December 14, 2004). This document describes a device that allows for the determination of the particle size of various powders on-line and in a relatively simple manner. This device is equipped with a spring whose spacing of the coils will enable the passage of different particle size measurement categories of particles which vary according to the amplitude of the vibration of the spring. However, such a device still poses new problems for those skilled in the art, although it has indeed been able to characterize the particle size measurement of various powders on-line. In fact, as indicated by the overview of the cover page of the document, when the particles of powder to be analyzed fall into the receiving chamber above the spring, they create a double disadvantage: their energy can be sufficiently large that when they Changing them when impacted by the spring (no longer guaranteeing the integrity of the material being tested), and/or damaging the spring by damaging the coils or by changing their spacing (the device is no longer guaranteed to be complete, And therefore the integrity of the measurement is no longer guaranteed).

Therefore, in order to solve his original technical problem, it is to develop a device for describing the characteristics of the particle size measurement of the powder on-line, which is simple to install in the industry and compatible with such industrial constraints, such as vibration. The Applicant has developed a device that satisfies these conditions at the same time, overcoming the shortcomings of U.S. Patent No. 6,829,955, which is incorporated herein by reference. Changes in the material being analyzed and damage to the measuring device.

The development of the device according to the invention appears to be particularly creative, since it never relies on documents that constitute the most recent state of the technology, and those skilled in the art will have to seek the document to use an obvious and natural Ways to improve.

Conversely, in a completely creative manner, the applicant has successfully recognized an older document in a larger set of documents, namely U.S. Patent No. 4,487,323, which is incorporated herein by reference. Documents based on sieves, screens or grids (17,789 files filed on May 8, 2006 in the B07B level of the International Patent Classification) have significantly changed their operations in order to solve their technology. problem.

The selection of this document is less than normal/obvious to those skilled in the art, as the prior art problems caused by the present application are not addressed in the U.S. Patent No. 4,487,323. In fact, the applicant is eager to emphasize the use of the device described in U.S. Patent No. 4,487,323, which is not capable of achieving the feature of the particle size measurement of the powder on-line. In fact, in order to characterize the particle size measurement of the powder, several human interventions are required in the document: the powder is introduced into the screening drum, especially during the introduction of the screen, the screen will be damaged ( And thus the risk of manually changing the screens or clogging (and thus manually cleaning the screens), and/or the powder when it comes into contact with the screens (and then the removal of the powder, The risk of changing the manual cleaning of the screen, and the new introduction of the powder to restart the measurement, and the cleaning/general maintenance of the device, and in particular the screens. Conversely, devices forming the subject of the present invention do not require any manual intervention during the screening cycle (however, the screens are not damaged/blocked, or the powder is modified) and the screens are not cleaned. Furthermore, it is equipped with a feed mechanism which enables it to be collected directly from its manufacturing process (for example by a feed hopper or by a cylindrical closed silo) for the analysis of the powder: making the device It is perfectly synchronized with the actual process of manufacture of the powder.

After having successfully recognized this document, the applicant has also successfully modified the device covered by the document to: - solve its original technical problems (even if it is possible to determine the particle size measurement of the powder online, and A simple way to comply with such industrial constraints, such as vibration); - simultaneously solve this initial technical problem, avoiding the shortcomings of the material used for testing and the damage to the measuring device, ie in the US patent document Disadvantages shown in US Pat. No. 6,829,955.

Therefore, in order to solve its original technical problem, that is, to make it possible to determine the particle size measurement of the powder online in a simple manner compatible with industrial constraints, the applicant has introduced a feeding mechanism which can be used for testing. The powder is introduced directly into the level screening facility; an institution that is not included in U.S. Patent No. 4,487,323. This choice will inevitably result in the sudden arrival of the powder for analysis on the screens, resulting in the possibility that the powder will be altered and/or the screens will be damaged: thus found in US Patent Document No. US The problem caused by No. 6 829 955, the demonstration of this choice is not normal. Therefore, one of the applicant's merits relates to the method in which it can solve the latter drawback: it is equipped with the horizontal screening mechanism, which is provided with an anti-impact plate member, which is not included in the US patent. In document No. 4,487,323, the panel has an impact resistance feature because it is initially positioned at the lowest position during the measurement cycle to receive the powder for testing. The screens are no longer damaged and the powder used for testing is no longer altered to ensure the integrity of both. The impact plate is actually a stainless steel frame equipped with a mat made of a natural rubber (high abrasion resistance) and a polyoxylized gel. A particular feature of the gelled body is that it absorbs the energy of the impact to prevent any rebound of the product without returning it.

Thus, through the present invention, those skilled in the art have a device capable of describing the characteristics of the powder on-line, the device being simple to use and compatible with the vibrations present in an industrial production unit, which will not The powder used for the analysis is altered and does not cause damage upon contact with the powder: this constitutes a major need for those skilled in the art.

Finally, there are two other minor advantages obtained by the present invention which are not provided in U.S. Patent No. 4,487,323. The Applicant emphasizes that these two other advantages are not related to this new technical issue as they can be linked to the original technical issue, as previously presented. Insofar as the solution only constitutes a selective feature of the invention, the Applicant has only chosen to present them as secondary technical issues.

In the sense that the measuring mechanism is a part separated by the rest of the device, the device described in the first item in the U.S. Patent No. 4,487,323 is not easy to use: if I want to move The device, the measuring mechanism must therefore be moved, which requires a pair of operations. Tightening the measuring mechanism to the rest of the device will cause it to be dependent on the vibrations caused by the continuous vibrating mechanism and thus fail to provide a reliable measurement. Here, another merit of the applicant is based on the solution that has been implemented, and that the measuring mechanism is effectively tied to the rest of the device, but also at the level of the motor and the screening mechanism. An elastic coupling mechanism is installed between the shaft centers. In this way, the combination can supply a device that forms a single part (without requiring a large amount of operation for movement in the plant) and extending the useful life of the vibrating mechanism of the device. In fact, because the vibration system is capable of vibrating the rotating cage by applying vibration to the axis coupled to the vibration system, the applicant successfully observed the fact that the elastic coupling mechanism interrupts the A shaft/motor linkage that avoids transmitting the shock to the motor: by this mechanism, the life of the motor is increased. This resilient coupling mechanism can be, inter alia, an elastomer-based mechanism that is well known to those skilled in the art.

This second item relates to the simplified requirements for use and to the cleaning of the device. Here, the applicant's merits are based on the fact that it has been able to observe an automatic cleaning mechanism comprising at least one nozzle and/or an ultrasonic generator located on the periphery of the screening mechanism. And projecting compressed air onto the screen will enable one or more rotational operations in conjunction with the screens to completely and perfectly clean the entire apparatus in a short period of time.

Finally, the applicant is eager to indicate that it is familiar with the French patent No. 05 04917, and therefore only relates to novelty to the state of the technology (according to the Intellectual Property Code L611-14) The terms and conditions are also in accordance with Article 54(2) of the European Patent Convention). However, there is, among other things, a fundamental difference between the application and the present invention, in the position 4 of the rotating mechanism, in the case of the present invention, one of the positions is an impact resistant plate . Accordingly, a first object of the present invention is a device for describing characteristics of particle size measurement of a powder, comprising a feed mechanism, an emptying mechanism, a weighing mechanism, a continuous vibration mechanism, a screening mechanism, and a There may be a control mechanism, and is characterized in that: - the screening mechanism is a mechanism that rotates about a horizontal axis, and has at least one space for an unoccupied space or a space for release and introduction of powder. Position, at a position of 1 for an impact resistant panel, at least 2 positions for a screen of 2 different screen openings; and wherein the device has a cleaning mechanism consisting of at least one nozzle and/or one An ultrasonic generator on the periphery of the screening mechanism; and wherein the device has an elastic coupling mechanism between the horizontal axis of the screening mechanism and the continuous vibration mechanism.

The device is thus equipped with a feed mechanism (1) through which the powder for analysis enters the screening mechanism (2). Those skilled in the art will be able to design the feed mechanism to connect it to a cylindrical closed silo, a hopper, or any other location in the manufacturing process for the powder to be tested, so that at that location The powder is sampled for transport into a device that forms the subject of the present invention.

By this method, it is possible to determine the particle size measurement of the powder for testing on the line, which is one of the advantages of the present invention.

The screening mechanism is a mechanism that rotates about its horizontal axis (3), and in this drawing, the free space, the different screens, and the impact plate are not shown, The impact resistant panel forms part of the features of the screening mechanism (refer to Figure 2, which has been described in detail above). The continuous vibration mechanism (4) imparts its vibration to the axis (3) and transmits the vibration to the screening mechanism. The elastic coupling mechanism (5) limits the propagation of the vibration of the screening mechanism to the continuous vibration mechanism: the service life of the continuous vibration mechanism is increased by this means.

In this way, we have a device that forms a single component, that is, a device that is simple to use and that is particularly easy to move in a manufacturing plant, and that the service life of the continuous vibration mechanism of the device is extended: this constitutes the advantages of the present invention. one.

The particles of different particle size measurement levels for analysis pass through the screen of the screening mechanism, flow out through the evacuation mechanism (6), and the weight is finally quantified in the weighing mechanism (7).

Figure 2 schematically illustrates the cylindrical screening mechanism, in fact it is particularly possible to observe from section AA of Figure 1.

During the cycle in which the characteristics of the powder are described, the screening mechanism is configured such that the impact resistant panel (a) is positioned at the lowest position. In this way, the powder used for testing arrives directly on the plate (a) through the opening (e): the materials are not altered (especially they are not interrupted when in contact with the hard screen, as in In the case of the prior art), they are not allowed to damage the screens (in the case of the prior art): by this method, the integrity of the powder used for the analysis, and the integrity of the measuring device, And especially such screens are especially preserved. This is a major advantage provided by the present invention.

In fact, the device preserves the integrity of the powder used for analysis and is not damaged by the powder. On the subject of continued integrity of the materials used for analysis, the Applicant is eager to emphasize that this is an essential requirement so as not to distort the weighing measurement. However, as far as possible (and this is also a secondary advantage of the present invention), the fact that the powder reaches the impact resistant panel without damaging the impact resistant panel can be caused, for example, by the presence of the powder on the panel. Another non-destructive measurement, such as and not intended to be limiting, an optical measurement, such as a color measurement, is somewhat of particular importance in the case of mineral materials such as calcium carbonate. In addition, the device does not have the disadvantages of the previously discussed laboratory methods because it is inexpensive to manufacture, simple to install and use, and because its conditions of use are completely compatible with the industrial environment in which it is used (atmospherically rich) Powdery materials, impact, vibration, etc.).

Moreover, unlike other mechanical devices of the prior art, it is possible to characterize the number of particle size measurement levels of the particles in a single operation (without changing the screen or interrupting the measurement cycle). Finally, its simplification makes it perfectly designed to be suitable for use in any location in the manufacturing process of the mineral material, by which the on-line control of the particle size measurement of the particles is allowed, which is familiar to those skilled in the art. The basic goal.

This feature description loop can then begin. Once all of the powder used for analysis has been automatically placed on the impact resistant panel, the screening mechanism is rotated until the finest mesh screen (b) located adjacent to the impact resistant panel is attached The lowest position: the first particle size measurement level of the powder particles is then screened. This operation is repeated for the screen (c) located immediately adjacent to the screen (b), and the screen (c) has a larger screen than the screen (b), and then for the screen ( d) Repeating the operation, the screen (d) is immediately adjacent to the screen (c), and the screen (d) has a larger screen than the screen (c). Finally, after a final rotation, the rotating mechanism is positioned such that the unused space is positioned at the lowest position: the particles that remain in the cylinder are therefore emptied downwards and weighed on the balance .

This figure thus represents a device according to the invention which is equipped with 3 screens of different mesh openings (b, c and d); this number is not limiting and it has been recalled that a device forming the subject of the invention is required At least 2 screens with different mesh openings. The device is designed to manage several locations, and thus several screens are suitable for controlling the manufacturing process of the powder for analysis.

By this mechanism, due to the continuous position of the screening mechanism around its horizontal axis, the particles are transported to a screen having progressively large mesh openings: by means of this mechanism, the classification is done by size particle. A weighing system coupled to the apparatus is capable of measuring the mass of the particles, the diameter of the particles being less than the mesh of each of the screens: by this mechanism, by reporting each mass of the particles, such as A function of the particle size of the particles is obtained as a function of the total weight of the sample. The results obtained can be expressed as "pass" (percentage of particles across the screen), expressed as "rejected" (percentage of staying in the screen, ie opposite to "pass"), or according to Any other mechanism for the expression of the results of this pattern.

At the end of the cycle for characterizing the sample, the sample is returned to the manufacturing cycle during the automatic cleaning operation of the present invention (an operation known as "countercurrent washing"). The goal of this cleaning stage is to empty the powder present in the weighing mechanism to clean the screen of the screening mechanism, remove dust from the entire device, and reinstate the device (with a possible failure of the present invention) The starting position for starting and/or restoring, or the alternate position for starting a new cycle during use of the present invention).

It includes: - opening the weighing mechanism to empty the sample.

- Rotate the screening mechanism through one or more turns.

- projecting compressed air onto the rotating screens, in particular through nozzles located on either side of the screening mechanism, as indicated in Figure 2(f), or by being located on either side of the screening mechanism Ultrasonic waves generated by the generator are projected onto the rotating screens.

- Pumping dust raised by the compressed air.

- Place the device in its original position.

The dust raised by the compressed air can thus be sucked up by a vacuum pressure system (8 in Fig. 1) which is found in all industrial powder manufacturing sites.

If this is not the case, the system can be easily equipped with a separate vacuum pressure system.

The number of screens, the time spent on the screens by the particles, and the total mass of the particles initially introduced into the screening mechanism are all parameters that are familiar to the artist and will be able to modify what he wants to describe. The essence of the product of the feature.

In addition to the distribution of such particles as a function of their particle size measurement, the present invention allows for the use of only the screen of the largest mesh during a simplified cycle, and the location of the coarsest particles, the analyzed powder by the oversized diameter The perception of possible contamination of one of the particles, which contamination may not be present in the powder. These oversized diameter particles are present substantially in small amounts; therefore, a simplified cycle is required, and a high quality sample can be used as compared to the quality of the samples analyzed during a complete cycle.

Therefore, the first object of the present invention is a device for describing characteristics of particle size measurement of a powder, and is provided with a feeding mechanism, an emptying mechanism, a weighing mechanism, a continuous vibration mechanism, a screening mechanism, and a There may be a control mechanism, and is characterized in that: - the screening mechanism is a mechanism that rotates about a horizontal axis, and has at least one space for an unoccupied space or a space for release and introduction of powder. Position, at a position of 1 for an impact resistant panel, at least 2 positions for a screen of 2 different screen openings; and wherein the device has a cleaning mechanism consisting of at least one nozzle and/or one An ultrasonic generator on the periphery of the screening mechanism; and wherein the device has an elastic coupling mechanism between the horizontal axis of the screening mechanism and the continuous vibration mechanism.

The feeding, emptying, weighing, and continuous vibrating mechanisms can be made with all of the mechanisms that are well known to those skilled in the art.

The same principle applies to the screening mechanism, provided that it rotates about a horizontal axis, and has at least 4 positions corresponding to 2 screens of different mesh openings, for the introduction of the powder and the release of the coarsest particles. There is no space to use, and 1 impact resistant panel.

The device is also characterized in that the impact resistant member is made of stainless steel and is equipped with a mat made of natural rubber and polyoxygenated gel.

The device is also characterized in that the resilient coupling mechanism is based on an elastomer.

The device according to the invention is also characterized in that the screening mechanism is produced in different shapes, and in particular cylindrical or polygonal.

If applicable, the device forming the subject matter of the present invention can thus comprise a control mechanism whose function controls other mechanisms. The control mechanism can be mechanically mounted or offset. It can be a computer, a programmable controller, or any other control mechanism that is well known to those skilled in the art.

Another object of the invention is to use the previously described apparatus to determine the particle size measurement of the powder.

The use of the device according to the invention is also characterized in that the device is capable of determining the particle size measurement of the powder by means of different successive positions which are obtained by the screening mechanism around its horizontal axis, the initial of the screening mechanism The position is at the lowest point where the impact resistant panel is positioned.

This application is also characterized in that the determination of the particle size measurement of the particles occurs on-line, that is, in the progress of the manufacturing process of the particles.

This application is characterized in that the powders are dry powders, i.e., powders having a water content of less than 5 mass percent, and preferably less than 2 mass percent, and most preferably less than 1 mass percent, such as It is determined by the difference weighing operation before and after drying of the powder.

This application is also characterized in that the powders have a particle size measurement range such that the average diameter of the powders is between 0.05 and 10 mm, preferably between 0.1 and 5 mm, and is excellently Between 0.2 and 2 mm.

This application is also characterized in that the powders are used in the food production field, such as powders based on sugar crystals, salt powder, flour, milk powder, powders composed of dehydrated food materials, washing powders, ceramic powders. , plastic powder, metal powder, paint powder, pharmaceutical powder, toner for printing, fertilizer, or powder composed of mineral matter, and even more particularly natural and/or precipitated based on calcium carbonate And/or a mineral powder based on dolomite and/or based on talc, and even more particularly a powder having a mineral material based on natural calcium carbonate, which is marble, chalk, limestone, Or a mixture thereof.

The following examples illustrate the invention but are not intended to limit its scope.

example Example 1

This example illustrates the use of the present invention is described for a powder of a particle size measured characteristic, the powder based thereon by the company OMYA ^TM Salles (France) made in the factory, and then the name of Durcal ^TM 130 Calcium carbonate sold under.

To accomplish this, the apparatus according to the present invention is equipped with four screens having a mesh size equal to 100 micrometers, 250 micrometers, 355 micrometers, and 500 micrometers, satisfying the analytical requirements of the above powder (customer quality specifications, etc.). At the location for the release of the coarsest particles, the time spent on the screen by the powder is equal to 06:00 minutes, 07:30 minutes, 04:00 minutes, 00:30 minutes, respectively. And the last 00:25 minutes.

The results of these correspondences are indicated in Table 1, which is expressed as a percentage of the particles, the diameter of which is greater than the size of each screen (referred to as a rejection).

Thus Table 1 demonstrates that it is possible to obtain a particle size measurement distribution of a powder such as calcium carbonate using the apparatus according to the invention.

Example 2

The purpose of this example is to demonstrate the reliability of the apparatus according to the present invention by illustrating the correlation between the measurements made with the apparatus on the same sample and the measurements made manually in the laboratory.

This example uses a powder, the powder-based thereon by the company OMYA ^TM Salles (France) made in the factory, and then marketed under the name of Durcal ^TM 130 calcium carbonate.

The different samples of the powder were analyzed according to the apparatus of the present invention under the same conditions as those described in Example 1.

At the same time, the samples were manually screened through a 100 micron screen and another 250 micron screen.

At the end of this document, Figures 3 and 4 respectively represent the measured rejection values (ordinate axis, or y-axis) according to the manual test of the laboratory, such as a rejection value (horizontal axis, or x-axis) measured according to the present invention. A function of: - at 100 microns (shown in Figure 3, the linear regression of the equation is y = 1.018x, and its regression coefficient is equal to 0.9751); - at 250 microns (shown in Figure 4, in this equation The linear regression linear system y = 1.1437x, and its regression coefficient is equal to 0.9856).

The readings of Figures 3 and 4 demonstrate an excellent correlation between the measurements made manually at 100 microns and 250 microns, and those measurements are obtained directly on the same sample by the device according to the invention (this correlation) naturally, different from the system may be used on products Durcal ^TM 130, the particle size and for other measuring points, such as 63 microns, 80 microns, 355 microns, etc.).

Example 3

This example illustrates the application of the present invention is described for the measurement of a particle size characteristics of the powder, the powder of a crystalline powder-based forms of sugar, and by the company Cristal Union ^TM thereon Corbeilles (France) made in the factory, And then sold in the form of powdered sugar.

To achieve this, the apparatus according to the present invention is equipped with five screens having a mesh size equal to 125 micrometers, 250 micrometers, 500 micrometers, 630 micrometers, and 800 micrometers, satisfying the analysis requirements of the above powder (customer quality specifications, etc.) . At the location for the release of the coarsest particles, the time spent on the screen by the powder is equal to 06:30 minutes, 06:00 minutes, 06:00 minutes, 05:00 minutes, respectively. , 03:30 minutes, and finally 02:30 minutes.

The results of these correspondences are indicated in Table 2, which is expressed as a percentage of the particles, the diameter of which is greater than the mesh of each screen (referred to as a rejection).

Table 2 therefore demonstrates that it is possible to obtain a particle size measurement distribution of a powder such as sugar using the apparatus according to the invention.

Example 4

The purpose of this example is to demonstrate the reliability of the apparatus according to the present invention by illustrating the correlation between the measurements made with the apparatus on the same sample and the measurements made manually in the laboratory. This example uses a powder, the powder-based company by the Cristal Union ^TM thereon Corbeilles (France) made in the factory, and then the name Candy ^TM sold crystallization of sugar.

The different samples of the powders were analyzed by the apparatus according to the invention under the same conditions as those described in Example 3. At the same time, the samples were manually screened through a 250 micron screen and another 630 micron screen.

At the end of this document, Figures 5 and 6 respectively represent the measured rejection values (ordinate axis, or y-axis) according to the manual test of the laboratory, such as a rejection value (horizontal axis, or x-axis) measured according to the present invention. A function of: - at 250 microns (shown in Figure 5, the linear regression of the equation in this equation is y = 1.0175x-1.51, and its regression coefficient is equal to 0.986); - at 630 microns (shown in Figure 6, here) The linear regression of the equation is y = 0.9773x-0.6 and its regression coefficient is equal to 0.988).

The readings of Figures 5 and 6 demonstrate an excellent correlation between the measurements made manually at 250 microns and 630 microns, and those measurements are obtained directly on the same sample by the device according to the invention (this correlation) Naturally, it may be used in different types of crystallized sugars, and for other particle size measurement points, such as 125 microns, 500 microns, 800 microns, etc.).

1. . . Feeding mechanism

2. . . Screening agency

3. . . Horizontal axis

4. . . Continuous vibration mechanism

5. . . Elastic coupling mechanism

6. . . Emptying mechanism

7. . . Weighing mechanism

8. . . Vacuum pressure system

a. . . Impact resistant plate

b. . . Screen

c. . . Screen

d. . . Screen

e. . . Opening

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic top plan view of a device forming the subject of the present invention; the hatched portion represents the frame, and the device forming the subject of the present invention is fastened to the frame for A joint is formed between the different mechanisms of the device.

Figure 2 shows schematically a cylindrical screening mechanism.

Figure 3 shows the rejection values measured in accordance with the present invention.

Figure 4 shows the rejection values measured in accordance with the present invention.

Figure 5 shows the rejection values measured in accordance with the present invention.

Figure 6 shows the rejection values measured in accordance with the present invention.

1. . . Feeding mechanism

2. . . Screening agency

3. . . Horizontal axis

4. . . Continuous vibration mechanism

5. . . Elastic coupling mechanism

6. . . Emptying mechanism

7. . . Weighing mechanism

8. . . Vacuum pressure system

Claims (19)

A device for characterizing a particle size measurement of a powder, the device being provided with a feed mechanism, an emptying mechanism, a weighing mechanism, a continuous vibration mechanism, a screening mechanism, and possibly a control mechanism, and characterized by: - wherein the screening mechanism is a mechanism that rotates about a horizontal axis, having at least one position for an unoccupied space or a space for release and introduction of powder, for use in having one of the impact absorbing mats a position of the impact resistant plate member and at least 2 positions of the 2 mesh screens for different mesh openings; and wherein the device has a cleaning mechanism consisting of at least one nozzle and/or one at the screening mechanism An ultrasonic generator on the periphery; and the device has an elastic coupling mechanism between the horizontal axis of the screening mechanism and the continuous vibration mechanism. A device for characterizing a particle size measurement of a powder according to the first aspect of the invention, wherein the screening mechanism is cylindrical or polygonal in shape. A device for characterizing particle size measurement of powder according to claim 1 or 2, wherein the impact plate member is made of stainless steel and is equipped with a natural rubber and a polyoxygenated gel. Into the mat. A device for characterizing particle size measurement of a powder according to claim 1 or 2, wherein the elastic coupling mechanism is based on an elastomer. A device for characterizing particle size measurement of a powder according to claim 1 or 2, wherein the device has a mechanically mounted or offset control mechanism, preferably a computer or a programmable Controller. One for use as claimed in any one of claims 1 to 5 A method of apparatus for characterizing particle size measurement of a powder for use in the determination of particle size measurement of a powder, wherein the method of use is capable of determining the particle size measurement of the powder by a different continuous position, the positions being surrounded by the screening mechanism Obtained by the horizontal axis, the initial position of the screening mechanism is where the impact resistant panel is positioned at the lowest point. A method of using a device for characterizing particle size measurement of a powder according to item 6 of the patent application, wherein the determination of the particle size measurement of the powder occurs on-line, that is, in the progress of the manufacturing process of the powder. A method of using a device for characterizing a particle size measurement of a powder according to claim 6 or 7, wherein the powder is a dry powder having a water content of less than 5 mass%, preferably less than 2 mass The percentage, which is preferably less than 1 mass percent, is determined by the differential weighing operation before and after drying of the powder. A method of using a device for characterizing particle size of a powder according to claim 6 or 7, wherein the powder has a particle size measuring range such that the average diameter of the powders is between 0.05 and 10 mm, It is preferably between 0.1 and 5 mm, and is preferably between 0.2 and 2 mm. A method of using a device for characterizing particle size measurement of a powder according to claim 6 or 7, wherein the powder is used in the powder of the food production field, and is preferably a powder based on sugar crystals. , salt powder, flour, milk powder, or a powder consisting of dehydrated food materials. A method of using a device for characterizing a particle size measurement of a powder according to claim 6 or 7, wherein the powder is a detergent. A method of using a device for characterizing particle size measurement of a powder according to claim 6 or 7, wherein the powder is a ceramic powder. A method of using a device for characterizing particle size of a powder according to claim 6 or 7, wherein the powder is a plastic powder. A method of using a device for characterizing particle size of a powder according to claim 6 or 7, wherein the powder is a metal powder. A method of using a device for characterizing particle size of a powder according to claim 6 or 7, wherein the powder is a paint powder. A method of using a device for characterizing particle size of a powder according to claim 6 or 7, wherein the powder is a drug powder. A method of using a device for characterizing particle size measurement of a powder according to claim 6 or 7, wherein the powder is used for printing carbon powder. A method of using a device for characterizing a particle size measurement of a powder according to claim 6 or 7, wherein the powder is a fertilizer. A method of using a device for characterizing particle size of a powder according to claim 6 or 7, wherein the powder is a powder composed of a mineral material, and even more particularly has a natural and/or precipitated A mineral material powder of a matrix of calcium carbonate and/or dolomite and/or talc, and even more particularly a mineral material powder of a matrix having natural calcium carbonate, the mineral material being marble, chalk, limestone, or a mixture thereof.